1. Field of the Invention
The present invention relates to a positioning device for a switch member of a reversible ratchet-type wrench.
2. Description of the Related Art
U.S. Pat. No. 2,957,377 issued to Hare on Oct. 25, 1960 discloses a reversible ratchet type wrench comprising a body 10 having a handle 11 and a head 12. A cap 39 and an annular wall 44 are provided to upper side and lower side of the head 12, respectively. Yet, this increases the assembly time and the manufacture cost and adversely affects the appearance. A shifting lever 35 is retained in place by a spring 33 that is located in a cylindrical opening 34. Nevertheless, formation of the cylindrical opening 34 that extends at an incline upward is relatively difficult. In addition, formation of the cavity 16 having converging straight sides 17, 18 which diverge in the direction of the periphery of rotatable member 14 requires expensive and accurate computer-numeric-control (CNC), which further results in an increase in the cost together with a low production rate. This is why such a reversible ratchet type wrench is hardly seen in the market.
FIGS. 9 and 10 illustrate another conventional ratchet type wrench comprising a handle 12xe2x80x2 and a head 11xe2x80x2. The head 11xe2x80x2 is machined to form four consecutive compartments for receiving the drive member 20xe2x80x2, the pawl 30xe2x80x2 and the shifting lever 40xe2x80x2, wherein three of the compartments can be formed by cutting, yet the remaining one must be machined by CNC. Further, the resultant head structure is relatively weak and thus has a poor torque-bearing capacity. In addition, the movement of the pawl 30xe2x80x2 for changing ratcheting direction is found unreliable, as it is achieved via transmission of the hook end 442xe2x80x2 of a spring 44xe2x80x2 attached to the shifting lever 40xe2x80x2.
It is the primary object of the present invention to provide a positioning device for a switch member of a reversible ratchet-type wrench. The resultant ratchet-type wrench is easy to manufacture and assemble.
It is another object of the present invention to provide a reversible ratchet-type wrench that can be manufactured within a relatively short period of time at low cost without using computer-controlled lathes.
A reversible ratchet-type wrench in accordance with the present invention comprises:
a handle;
a head extended from the handle and having a hole, a web being defined between the handle and the head, the web including a cavity communicated with the hole of the head and a receiving hole communicated with the cavity, an inner periphery defining the receiving hole including a first positioning notch and a second positioning notch;
a drive member rotatably mounted in the hole of the head and including a plurality of teeth defined in an outer periphery thereof;
a pawl mounted in the cavity and including a first side facing the hole of the head and a second side facing away from the hole of the head, the first side of the pawl including a plurality of teeth for meshing with the teeth of the drive member;
a switch member including a turn-piece outside the receiving hole of the web for manual operation, the switch member further including a positioning section extending from the turn-piece and a switching section extending from the positioning section, the positioning section being rotatably received in the receiving hole of the web and having a positioning member retained in one of the first positioning notch and the second positioning notch of the receiving hole of the web, the turn-piece being movable to move the positioning member into one of the first positioning notch and the second positioning notch; and
a biasing/actuating means having a first end attached to the positioning section of the switch member and a second end attached to the second side of the pawl for biasing the teeth of the first side of the pawl to engage with the teeth of the drive member;
wherein when the positioning member is retained in the first positioning notch of the receiving hole of the web, the wrench allows ratcheting in a first direction, and when the positioning member is retained in the second positioning notch of the receiving hole of the web, the wrench allows ratcheting in a second direction that is reverse to the first direction.
The receiving hole is a cylindrical hole extending along a direction that is perpendicular to a longitudinal axis of the handle. The second side of the pawl includes a recess. An inner wall defining the recess includes an arcuate groove for receiving the second end of the biasing/actuating means. The biasing/actuating means includes an actuating member and an elastic member. The actuating member has a wider middle portion, a first end, and a second end. The elastic member includes a first end attached to the first end of the actuating member and a second end attached to the switching section of the switch member. The second end of the actuating member is biased by the elastic member into the arcuate groove of the pawl. The second end of the actuating member is round. The switching section of the switch member includes a receptacle for receiving the second end of the elastic member. Two reinforcing pieces project outward from an area that surrounds an end of the receptacle, and the middle portion of the actuating member are guided between the reinforcing pieces.
The positioning section of the switch member includes two opposite flat sides to allow slight sliding movement of the switch member in the receiving hole of the web. Each of the two positioning notches includes an inclined section adjacent to the other positioning notch to guide the positioning member out of one of the positioning notches and into the other positioning notch.
An inner periphery defining the hole of the head includes an annular groove. The outer periphery of the drive member includes an annular groove. A C-clip is received in the annular groove of the head and the annular groove of the drive member, thereby rotatably mounting the drive member in the head. The drive member may be a gear wheel.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.